Dash in layout filenames
[issue link]If layout component file name contains special characters, this leads to incorrect App.vue generation:
as an example: (layouts/docs-components.vue)
let layouts = {
_docs-components: process.BROWSER_BUILD ? () => System.import('...docs-components.vue') : require('...docs-components.vue'),
}
This throws syntax errors. keys can be easily quated to avoid this problem.